System and method for mapping complex fractionated electrogram information

ABSTRACT

A system for presenting information representative of patient electrophysiological activity, such as complex fractionated electrogram information, includes at least one electrode to measure electrogram information from the heart surface, at least one processor coupled to the at least one electrode to receive the electrogram information and measure a location of the at least one electrode within the heart, and a presentation device to present the electrogram information as associated with the location at which it was measured on a model of the patient&#39;s heart. A memory may also be provided in which to store the associated electrogram information and measured location. Data may be analyzed using both time-domain and frequency-domain information to create a three-dimensional map. The map displays the data as colors, shades of color, and/or grayscales, and may further utilize contour lines, such as isochrones, to present the information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.11/227,006, filed 15 Sep. 2005, which is hereby expressly incorporatedby reference as though fully set forth herein.

This application claims the benefit of U.S. provisional application No.60/800,852, filed 17 May 2006, which is hereby expressly incorporated byreference as though fully set forth herein.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The instant invention relates to an electrophysiology apparatus used tomeasure electrical activity occurring in a heart of a patient and tovisualize the electrical activity and/or information related to theelectrical activity. In particular, the instant invention relates tothree-dimensional mapping of the electrical activity associated withcomplex fractionated electrograms and/or the information related to thecomplex fractionated electrograms.

b. Description of the Prior Art

The heart contains two specialized types of cardiac muscle cells. Themajority, around ninety-nine percent, of the cardiac muscle cells iscontractile cells, which are responsible for the mechanical work ofpumping the heart. Autorhythmic cells comprise the second type ofcardiac muscle cells, which function as part of the autonomic nervoussystem to initiate and conduct action potentials responsible for thecontraction of the contractile cells. The cardiac muscle displays apacemaker activity, in which membranes of cardiac muscle cells slowlydepolarize between action potentials until a threshold is reached, atwhich time the membranes fire or produce an action potential. Thiscontrasts with a nerve or skeletal muscle cell, which displays amembrane that remains at a constant resting potential unless stimulated.The action potentials, generated by the autorhythmic cardiac musclecells, spread throughout the heart triggering rhythmic beating withoutany nervous stimulation.

The specialized autorhythmic cells of cardiac muscle comprising theconduction system serve two main functions. First, they generateperiodic impulses that cause rhythmical contraction of the heart muscle.Second, they conduct the periodic impulses rapidly throughout the heart.When this system works properly, the atria contract about one sixth of asecond ahead of ventricular contraction. This allows extra filling ofthe ventricles before they pump the blood through the lungs andvasculature. The system also allows all portions of the ventricles tocontract almost simultaneously. This is essential for effective pressuregeneration in the ventricular chambers. The rates at which theseautorhythmical cells generate action potentials differ due todifferences in their rates of slow depolarization to threshold in orderto assure the rhythmical beating of the heart.

Normal autorhythmic cardiac function may be altered by neuralactivation. The medulla, located in the brainstem above the spinal cord,receives sensory input from different systemic and central receptors(e.g., baroreceptors and chemoreceptors) as well as signals from otherbrain regions (e.g., the hypothalamus). Autonomic outflow from thebrainstem is divided principally into sympathetic and parasympathetic(vagal) branches. Efferent fibers of these autonomic nerves travel tothe heart and blood vessels where they modulate the activity of thesetarget organs. The heart is innervated by sympathetic and vagal fibers.Sympathetic efferent nerves are present throughout the atria (especiallyin the sinoatrial node) and ventricles, including the conduction systemof the heart. The right vagus nerve primarily innervates the sinoatrialnode, whereas the left vagus nerve innervates the atrial-ventricularnode; however, there can be significant overlap in the anatomicaldistribution. Efferent vagal nerves also innervate atrial muscle.However, efferent vagal nerves only sparsely innervate the ventricularmyocardium. Sympathetic stimulation increases heart rate and conductionvelocity, whereas parasympathetic (vagal) stimulation of the heart hasopposite effects.

An arrhythmia occurs when the cardiac rhythm becomes irregular, i.e.,too fast (tachycardia) or too slow (bradycardia), or the frequency ofthe atrial and ventricular beats are different. Arrhythmias can developfrom either altered impulse formation or altered impulse conduction. Theformer concerns changes in rhythm that are caused by changes in thepacemaker cells resulting in irregularity or by abnormal generation ofaction potentials by sites other than the sinoatrial node, i.e., ectopicfoci. Altered impulse conduction is usually associated with complete orpartial blockage of electrical conduction within the heart. Alteredimpulse conduction commonly results in reentry, which can lead totachyarrhythmias. Reentry can take place within a small local region orit can occur, for example, between the atria and ventricles (globalreentry). Reentry requires the presence of a unidirectional block withina conducting pathway usually caused by partial depolarization of thepacemaker cells. Arrhythmias can be either benign or more serious innature depending on the hemodynamic consequences of arrhythmias andtheir potential for changing into lethal arrhythmias.

Electrophysiology studies may be used to identify and treat thesearrhythmias. In one exemplary system, a measurement system introduces amodulated electric field into the heart chamber. The blood volume andthe moving heart wall surface modify the applied electric field.Electrode sites within the heart chamber passively monitor themodifications to the field and a dynamic representation of the locationof the interior wall of the heart is developed for display to thephysician. Electrophysiology signals generated by the heart itself arealso measured at electrode sites within the heart and these signals arelow pass filtered and displayed along with the dynamic wallrepresentation. This composite dynamic electrophysiology map may bedisplayed and used to diagnose the underlying arrhythmia.

In addition to mapping for diagnosis, the measurement system can also beused to physically locate a therapy catheter in a heart chamber. Amodulated electrical field delivered to an electrode on this therapycatheter can be used to show the location of the therapy catheter withinthe heart. The therapy catheter location can be displayed on the dynamicelectrophysiology map in real time along with the other diagnosticinformation. Thus the therapy catheter location can be displayed alongwith the intrinsic or provoked electrical activity of the heart to showthe relative position of the therapy catheter tip to the electricalactivity originating within the heart itself. Consequently, thephysician can guide the therapy catheter to any desired location withinthe heart with reference to the dynamic electrophysiology map.

The dynamic electrophysiology map is generally produced in a step-wiseprocess. First, the interior shape of the heart is determined. Thisinformation is derived from a sequence of geometric measurements relatedto the modulation of the applied electric field. Knowledge of thedynamic shape of the heart is used to generate a representation of theinterior surface of the heart. Next, the intrinsic electrical activityof the heart is measured. The signals of physiologic origin arepassively detected and processed such that the magnitude of thepotentials on the wall surface may be displayed on the wall surfacerepresentation. The measured electrical activity is displayed on thewall surface representation in any of a variety of formats, for example,in various colors or shades of a color. Finally, a location current maybe delivered to a therapy catheter within the same chamber. Thepotential sensed from this current may be processed to determine therelative or absolute location of the therapy catheter within thechamber. These various processes occur sequentially or simultaneouslyseveral hundred times a second to give a continuous image of heartactivity and the location of the therapy device.

One exemplary system for determining the position or location of acatheter in the heart is described in U.S. Pat. Nos. 5,697,377 (the '377patent) and 5,983,126 (the '126 patent) to Wittkampf. The '377 patentand the '126 patent are hereby incorporated herein by reference in theirentirety. In the Wittkampf system, current pulses are applied toorthogonally placed patch electrodes placed on the surface of thepatient. These surface electrodes are used to create axis specificelectric fields within the patient. The Wittkampf references teach thedelivery of small amplitude, low current pulses supplied continuously atthree different frequencies, one on each axis. Any measurement electrodeplaced in these electric fields (for example within the heart) measuresa voltage that varies depending on the location of the measurementelectrode between the various surface electrodes on each axis. Thevoltage across the measurement electrode in the electric field inreference to a stable positional reference electrode indicates theposition of the measurement electrode in the heart with respect to thatreference. Measurement of the difference in voltage over the threeseparate axes gives rise to positional information for the measurementelectrode in three dimensions.

BRIEF SUMMARY OF THE INVENTION

The present invention expands the previous capabilities of cardiacelectrophysiology mapping systems to provide additional diagnostic datausing both the time-domain and frequency-domain representations ofelectrophysiology data. A three-dimensional map of the electricalactivity and/or the information related to the electrical activity iscreated. Exemplary maps include a time difference between actionpotentials at a roving electrode and a reference electrode, thepeak-to-peak voltage of action potentials at the roving electrode, thepeak negative voltage of action potentials at the roving electrode,complex fractionated electrogram information, a dominant frequency of anelectrogram signal, a maximum peak amplitude at the dominant frequency,a ratio of energy in one band of the frequency-domain to the energy in asecond band of the frequency-domain, a low-frequency or high-frequencypassband of interest, a frequency with the maximum energy in a passband,a number of peaks within a passband, an energy, power, and/or area ineach peak, a ratio of energy and/or area in each peak to that in anotherpassband, and a width of each peak in a spectrum. Colors, shades ofcolor, and/or grayscales are assigned to values of the parameters andcolors, shades of colors, and/or grayscales corresponding to theparameters for the electrograms sampled by the electrodes are updated onthe three-dimensional model. Maps may be presented by utilizing contourlines, such as isochrones.

According to a first embodiment of the invention, a system forpresenting information representative of electrophysiological activityof a patient includes: at least one electrode adapted to receive atleast one stream of electrical data from at least one location within aheart of a patient, the data including complex fractionated electrograminformation; at least one processor coupled to the at least oneelectrode to receive the at least one stream of electrical data from atleast one location and to determine the measurement location of theelectrode within the heart of the patient while it is receiving thestream of electrical data, the at least one processor associating themeasurement location with the at least one stream of electrical databeing received; at least one memory to store the measurement location ofthe electrode and the at least one stream of electrical data beingreceived; software to analyze the at least one stream of electrical datato identify occurrences of discrete electrical activations within apredetermined window and to quantify the complex fractionatedelectrogram information contained in the predetermined window; and apresentation device to present the quantified complex fractionatedelectrogram information and its respective measurement location on amodel of the heart of the patient. The software may quantify thestandard deviation, the mean, or both the standard deviation and themean of the time intervals between occurrences of discrete electricalactivations, which may then be presented on the model at a locationcorresponding to a point at which the electrical data was measured. Thesystem may optionally employ a plurality of electrodes simultaneouslyreceiving electrical data from a plurality of locations within thepatient.

According to another aspect of the invention, a method of analyzing andpresenting information representative of electrophysiologicalinformation of a patient includes the steps of: obtaining a cardiacelectrophysiology map including position information identifying aplurality of measurement locations and electrophysiology measurementsmade at each of the plurality of measurement locations, theelectrophysiology measurements including at least one stream of complexfractionated electrogram information; processing the at least one streamof complex fractionated electrogram information measured at one of theplurality of measurement locations to identify occurrences of discreteelectrical activations within a predetermined window and to quantify thecomplex fractionated electrogram information contained in thepredetermined window; and presenting the quantified complex fractionatedelectrogram information and its respective measurement location on amodel of the heart of the patient. The method optionally employs aplurality of electrodes simultaneously receiving electrical data from aplurality of measurement locations within the patient, which may beprocessed, quantified, and presented on the model. The complexfractionated electrogram information may be presented on the model ascolors, shades of colors, or a grayscale.

In yet another aspect of the present invention, a method of analyzingand presenting information representative of electrophysiologicalactivity of a patient includes the steps of: obtaining a cardiacelectrophysiology map including position information identifying ameasurement location and electrophysiology measurements made at themeasurement locations, the electrophysiology measurements including atleast one stream of complex fractionated electrogram information;processing the at least one stream of complex fractionated electrograminformation measured at the measurement locations to identifyoccurrences of discrete electrical activations within a predeterminedwindow and to quantify the standard deviation of the time intervalsbetween occurrences of discrete electrical activations within thepredetermined window; and presenting the standard deviation informationon the model of the heart at a location corresponding to a point wherethe at least one stream of complex fractionated electrogram informationwas measured.

In still another embodiment, a system for presenting informationrepresentative of electrophysiological activity of a patient includes:at least one electrode adapted to measure electrogram information from asurface of a heart of a patient; at least one processor coupled to theat least one electrode to receive the electrogram information and tomeasure a location of the at least one electrode within the heart of thepatient at which the electrogram information is measured, wherein the atleast one processor associates the measured location of the at least oneelectrode with the received electrogram information; and a presentationdevice to present the associated electrogram information and measuredlocation on a model of the heart of the patient. The electrograminformation optionally includes complex fractionated electrograminformation. A memory may also be provided in which to store theassociated electrogram information and measured location.

According to a further aspect of the invention, a method of presentinginformation representative of patient electrophysiologicalcharacteristics on a model of a surface of a heart includes the stepsof: a) introducing at least one electrode into the heart; b) measuringelectrogram information from the surface of the heart via the at leastone electrode; c) measuring location information of the at least oneelectrode; d) deriving, from the measured location information, locationinformation for a point on the surface of the heart at which theelectrogram information is measured; e) associated the derived locationinformation and measured electrogram information; and f) presentinginformation indicative of the associated location information andelectrogram information on the model of the surface of the heart. Stepsb) through f) may be repeated a plurality of times as the electrodemoves within the heart. Alternatively, steps b) through f) may berepeated for a plurality of electrodes introduced into the heart.

The foregoing and other aspects, features, details, utilities, andadvantages of the present invention will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a system for performing a cardiacelectrophysiology examination or ablation procedure wherein the locationof one or more electrodes can be determined and recorded.

FIG. 2 is a schematic representation of a heart investigated by anelectrophysiology catheter with several distal electrodes.

FIG. 3 is a schematic diagram of an exemplary methodology for renderinga surface of a heart cavity using recorded electrode position datapoints.

FIG. 4 is a schematic depiction of a graphical user interface fordisplaying electrocardiograph and related electrophysiologicalinformation to a clinician.

FIG. 5 is an enlargement of the panel 66 depicted in FIG. 4.

FIG. 6 shows side-by-side views of time-varying electrograms collectedfor various locations along a wall of a heart.

FIG. 7 shows side-by-side views of time-varying electrograms collectedfor various locations along a wall of a heart.

FIG. 8 shows side-by-side comparisons of electrograms for typicalcompact and fibrillar myocardial muscle tissues in the time-domain andfrequency-domain.

FIG. 9A shows a side-by-side comparison of time-domain andfrequency-domain information for electrograms.

FIG. 9B shows a side-by-side comparison of time-domain andfrequency-domain information for electrograms with energy in multiplespectral bands shown in cross-hatch.

FIG. 10 shows a method for collecting electrograms and mappingtime-domain and/or frequency-domain electrogram information on athree-dimensional model.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic diagram of a system 8 according to the presentinvention for conducting cardiac electrophysiology studies by measuringelectrical activity occurring in a heart 10 of a patient 11 andthree-dimensionally mapping the electrical activity and/or informationrelated to the electrical activity. In one embodiment, for example, thesystem 8 can instantaneously locate up to sixty-four electrodes inand/or around a heart and the vasculature of a patient, measureelectrical activity at up to sixty-two of those sixty-four electrodes,and provide a three-dimensional map of time domain and/or frequencydomain information from the measured electrical activity (e.g.,electrograms) for a single beat of the heart 10. The number ofelectrodes capable of being simultaneously monitored is limited only bythe number of electrode lead inputs into the system 8 and the processingspeed of the system 8. The electrodes may be stationary or may bemoving. In addition, the electrodes may be in direct contact with thewall of the heart, or may be merely generally adjacent to the wall ofthe heart, to collect the electrical activity. In another embodiment inwhich an array electrode is used, the system 8 can determineelectrograms for up to about 3000 locations along the wall of the heart.Such an array electrode is described in detail in U.S. Pat. No.5,662,108, which is hereby incorporated by reference herein in itsentirety.

The patient 11 is depicted schematically as an oval for simplicity.Three sets of surface electrodes (e.g., patch electrodes) are shownapplied to a surface of the patient 11 along an X-axis, a Y-axis, and aZ-axis. The X-axis surface electrodes 12, 14 are applied to the patientalong a first axis, such as on the lateral sides of the thorax region ofthe patient (e.g., applied to the patient's skin underneath each arm)and may be referred to as the Left and Right electrodes. The Y-axiselectrodes 18, 19 are applied to the patient along a second axisgenerally orthogonal to the X-axis, such as along the inner thigh andneck regions of the patient, and may be referred to as the Left Leg andNeck electrodes. The Z-axis electrodes 16, 22 are applied along a thirdaxis generally orthogonal to the X-axis and the Y-axis, such as alongthe sternum and spine of the patient in the thorax region and may bereferred to as the Chest and Back electrodes. The heart 10 lies betweenthese pairs of surface electrodes. An additional surface referenceelectrode (e.g., a “belly patch”) 21 provides a reference and/or groundelectrode for the system 8. The belly patch electrode 21 is analternative to a fixed intra-cardiac electrode 31. It should also beappreciated that in addition, the patient 11 will have most or all ofthe conventional electrocardiogram (ECG) system leads in place. This ECGinformation is available to the system 8 although not illustrated in theFIG. 1.

A representative catheter 13 having at least a single electrode 17(e.g., a distal electrode) is also shown. This representative catheterelectrode 17 is referred to as the “roving electrode” or “measurementelectrode” throughout the specification. Typically, multiple electrodeson the catheter will be used. In one embodiment, for example, the system8 may comprise up to sixty-four electrodes on up to twelve cathetersdisposed within the heart and/or vasculature of the patient. Of course,this embodiment is merely exemplary, and any number of electrodes andcatheters may be used within the scope of the present invention.

The fixed reference electrode 31 (e.g., attached to a wall of the heart10) is shown on a second catheter 29. For calibration purposes, thiselectrode 31 may be stationary (e.g., attached to or near the wall ofthe heart) or disposed in a fixed spatial relationship with the rovingelectrode 17. The fixed reference electrode 31 may be used in additionto or alternatively to, the surface reference electrode 21 describedabove. In many instances, a coronary sinus electrode or other fixedelectrode in the heart 10 can be used as a reference for measuringvoltages and displacements.

Each surface electrode is coupled to the multiplex switch 24, and thepairs of electrodes are selected by software running on a computer 20,which couples the electrodes to a signal generator 25. The computer 20,for example, may comprise a conventional general-purpose computer, aspecial-purpose computer, a distributed computer, or any other type ofcomputer. The computer 20 may comprise one or more processors, such as asingle central-processing unit, or a plurality of processing units,commonly referred to as a parallel processing environment.

The signal generator 25 excites a pair of electrodes, for example theY-axis electrodes 18, 19, which generates an electric field in the bodyof the patient 11 and the heart 10. During the delivery of the currentpulse, the remaining surface electrodes are referenced to the surfaceelectrode 21, and the voltages induced on these remaining electrodes arefiltered via a low pass filter (LPF) 27. The LPF 27 may, for example,comprise an anti-aliasing filter (e.g., a 300 Hz analog LPF). The outputof the LPF 27 is then provided to an analog-to-digital (A/D) converter26 that converts the analog signal to a digital data signal. Further lowpass filtering of the digital data signal may be subsequently performedby software executed on the computer 20 to remove electronic noise andcardiac motion artifact. This filtering may, for example, comprise auser-selectable cutoff frequency used to reduce noise. In this manner,the user can customize the system to trade off signal noise againstsignal fidelity according to the user's individual preferences. In thisfashion, the surface electrodes are divided into driven and non-drivenelectrode sets. A pair of surface electrodes (e.g., the X-axiselectrodes 12, 14) are driven by the signal generator 25, and theremaining, non-driven surface electrodes and other reference electrodes,if any, (e.g., the Y-axis electrodes 18, 19, the Z-axis electrodes 16,22, the surface reference electrode 21, and, if present, the fixedreference electrode 31) are used as references to synthesize theposition of any intracardial electrodes.

Generally, three nominally orthogonal electric fields are generated by aseries of driven and sensed electric dipoles in order to realizecatheter navigation in a biological conductor. Alternately, theseorthogonal fields can be decomposed and any pairs of surface electrodescan be driven as dipoles to provide effective electrode triangulation.Additionally, such nonorthogonal methodologies add to the flexibility ofthe system. For any desired axis, the potentials measured across anintra-cardiac electrode 17 resulting from a predetermined set of drive(source-sink) configurations are combined algebraically to yield thesame effective potential as would be obtained by simply driving auniform current along the orthogonal axes.

Thus, any two of the surface electrodes 12, 14, 16, 18, 19, 22 may beselected as a dipole source and drain with respect to a groundreference, e.g., the belly patch 21, while the unexcited electrodesmeasure voltage with respect to the ground reference. The measurementelectrode 17 placed in the heart 10 is exposed to the field from acurrent pulse and its voltage is measured with respect to ground, e.g.,with respect to the belly patch 21. In practice, the catheters withinthe heart may contain multiple electrodes, and each electrode potentialmay be measured. As previously noted, at least one electrode may befixed to the interior surface of the heart to form a fixed referenceelectrode 31, which is also measured with respect to ground. Data setsfrom each of the surface electrodes, the internal electrodes, and thevirtual references are all used to determine the location of themeasurement electrode 17 or other electrodes within the heart 10.

All of the raw electrode voltage data is measured by the A/D converter26 and stored by the computer 20 under the direction of software. Thiselectrode excitation process occurs rapidly and sequentially asalternate sets of surface electrodes are selected and the remainingnon-driven electrodes are used to measure voltages. This collection ofvoltage measurements is referred to herein as the “electrode data set.”The software has access to each individual voltage measurement made ateach electrode during each excitation of each pair of surfaceelectrodes.

The raw electrode data is used to determine the “base” location inthree-dimensional space (X, Y, Z) of the electrodes inside the heart,such as the roving electrode 17, and any number of other electrodeslocated in or around the heart and/or vasculature of the patient 11.FIG. 2 shows a catheter 13, which may be a conventionalelectrophysiology (EP) catheter, extending into the heart 10. In FIG. 2,the catheter 13 extends into the left ventricle 50 of the heart 10. Thecatheter 13 comprises the distal electrode 17 discussed above withrespect to FIG. 1 and has additional electrodes 52, 54, and 56. Sinceeach of these electrodes lies within the patient (e.g., in the leftventricle of the heart in this example), location data may be collectedsimultaneously for each of the electrodes. In addition, when theelectrodes are disposed adjacent to the surface, although notnecessarily directly on the surface of the heart, and when the signalsource 25 is “off” (i.e., when none of the surface electrode pairs isenergized), at least one of the electrodes 17, 52, 54, and 56 can beused to measure electrical activity (e.g., voltage) on the surface ofthe heart 10.

In summary, the system 8 first selects a set of electrodes and thendrives them with current pulses. While the current pulses are beingdelivered, electrical activity, such as the voltages measured at leastone of the remaining surface electrodes and in vivo electrodes aremeasured and stored. At this point, compensation for artifacts, such asrespiration and/or impedance shifting may be performed as indicatedabove. As described above, various location data points are collected bythe system 8 that are associated with multiple electrode locations(e.g., endocardial electrode locations). Each point in the set hascoordinates in space. In one embodiment, the system 8 collects locationdata points for up to sixty-four electrodes that may be located on up totwelve catheters simultaneously or in close proximity to one another.However, smaller or larger data sets may be collected and result in lesscomplex and lower resolution or more complex and higher resolutionrepresentations of the heart, respectively.

The electrode data may also be used to create a respiration compensationvalue used to improve the raw location data for the electrode locationsas described in U.S. Patent Application Publication No. 2004/0254437,which is hereby incorporated herein by reference in its entirety. Theelectrode data may also be used to compensate for changes in theimpedance of the body of the patient as described in co-pending U.S.patent application Ser. No. 11/227,580, filed contemporaneously withthis application on 15 Sep. 2005, which is also incorporated herein byreference in its entirety.

The data used to determine the location of the electrode(s) within theheart are measured while the surface electrode pairs impress an electricfield on the heart. A number of electrode locations may be collected byeither sampling a number (e.g., sixty-two electrodes spread among up totwelve catheters) simultaneously or in sequence (e.g., multiplexed)and/or by sampling one or more electrodes (e.g., the roving electrode17) being moved within the patient (e.g., a chamber of the heart). Inone embodiment, the location data for individual electrodes are sampledsimultaneously, which allows for collection of data at a single stage orphase of a heartbeat. In another embodiment, location data may becollected either synchronously with one or more phases of the heartbeator without regard for any particular stage of the heartbeat. Where thedata is collected across the phases of the heartbeat, data correspondingto locations along the wall of the heart will vary with time. In onevariation, the data corresponding to the outer or inner locations may beused to determine the position of the heart wall at the maximum andminimum volumes, respectively. For example, by selecting the mostexterior points it is possible to create a “shell” representing theshape of the heart at its greatest volume.

A three-dimensional model of a portion of the patient, e.g., a region ofthe patient's heart or surrounding vasculature, may be created from thelocation data points, e.g., during the same or a previous procedure, ora previously generated three-dimensional model, e.g., a segmented CT orMRI scan image, may be used. A segmented model indicates that asubregion of a three-dimensional image has been digitally separated froma larger three-dimensional image, e.g., an image of the right atriumseparated from the rest of the heart. Exemplary segmentationapplications include ANALYZE (Mayo, Minneapolis, Minn.), Verismo (St.Jude Medical, Inc., St. Paul, Minn.), and CardEP (General ElectricMedical Systems, Milwaukee, Wis.). Where the three-dimensional model iscreated from the location data points collected by the system 8, forexample, during a single procedure, the exterior-most location points inthe data can be used to determine a shape corresponding to the volume ofa region of the patient's heart.

In one variation, for example, a convex hull may be generated usingstandard algorithms such as the Qhull algorithm. The Qhull algorithm,for example, is described in Barber, C. B., Dobkin, D. P., andHuhdanpaa, H. T., “The Quickhull algorithm for convex hulls,” ACM Trans.on Mathematical Software, 22(4):469-483, December 1996. Other algorithmsused to compute a convex hull shape are known and may also be suitablefor use in implementing the invention. This surface is then re-sampledover a more uniform grid and interpolated to give a reasonably smoothsurface stored as a three-dimensional model for presentation to thephysician during the same or a later procedure. Such a three-dimensionalmodel, for example, provides an estimated boundary of the interior ofthe heart region from the set of points.

FIG. 3 schematically depicts another exemplary method for creating ashell corresponding to the shape of a heart chamber. The location dataidentifying position data points 40 of one or more electrodes within theheart chamber over a period of time is accessed. The location data maybe represented as a cloud of points within the heart chamber. The mostdistant position data points 40 will thus correspond to the interiorwall of the heart chamber in a relaxed or diastole state correspondingto its greatest volume. A shell or surface is rendered from thislocation data by fitting an array of “bins” 44 around groups of theposition data points 40. The bins 44 are constructed by determining amean center point 42 within the cloud of position data points 40 andthen extending borders radially outward from the center point 42. Thebins 44 extend to the furthest position data point 40 within the sliceencompassed by the bin 44. It should be noted that even though FIG. 3 isschematically presented in two dimensions, the bins 44 arethree-dimensional volumes. The radial end faces 46 of the bins 44 thusapproximate the surface of the heart chamber wall. Common graphicshading algorithms can then be employed to “smooth” the surface of theshell thus created out of the radial end faces 46 of the bins 44.

Various electrophysiology data may be measured and presented to acardiologist through the display 23 of the system 8 shown in FIG. 1.FIG. 4 depicts an illustrative computer display that may be displayedvia the computer 20. The display 23, for example, may be used to showdata to a user, such as a physician, and to present certain options thatallow the user to tailor the configuration of the system 8 for aparticular use. It should be noted that the contents on the display canbe easily modified and the specific data presented is illustrative onlyand not limiting of the invention. An image panel 60 shows athree-dimensional model of a heart chamber 62 identifying regions thatreceived a depolarization waveform at the same time, i.e., “isochrones,”mapped to the model in false color or grayscale. The isochrones are, inone variation, mapped to three-dimensional coordinates (e.g., X, Y, Z)corresponding to the electrogram from which they were obtained. Theisochrones are also shown in guide bar 64 as a key, identifyinginformation associated with a particular color or grayscale mapped tothe three-dimensional model. In this image, the locations of multipleelectrodes on a pair of catheters are also mapped to thethree-dimensional model. Other data that may be mapped to the heartsurface model include, for example, the magnitude of a measured voltageand the timing relationship of a signal with respect to heartbeatevents. Further, the peak-to-peak voltage measured at a particularlocation on the heart wall may be mapped to show areas of diminishedconductivity and may reflect an infarct region of the heart.

In the variation shown in FIG. 4, for example, the guide bar 64 isgraduated in milliseconds and shows the assignment of each color orgrayscale to a particular time relationship mapped to thethree-dimensional model. The relationship between the color or grayscaleon the three-dimensional model image 62 and the guide bar 64 can also bedetermined by a user with reference to the information shown in panel66. FIG. 5 shows an enlargement of the panel 66 depicted in FIG. 4. Thepanel 66, in this variation, shows timing information used to generateisochrones mapped on the three-dimensional model 62 shown in FIG. 4. Ingeneral, a fiducial point is selected as the “zero” time. In FIG. 5, forexample, the inflection point 70 of a voltage appearing on a referenceelectrode is used as the primary timing point for the creation ofisochrones. This voltage may be acquired from either a virtual referenceor a physical reference (e.g., the roving electrode 31 shown in FIG. 1).In this variation, the voltage tracing corresponding to the fiducialpoint is labeled “REF” in FIG. 5. The roving electrode signal isdepicted in FIG. 5 and is labeled “ROV.” The inflection point 72 of thevoltage signal ROV corresponds to the roving electrode 31. The colorguide bar 65 shows the assignment of color or grayscale tone for thetiming relationship seen between inflection points 70 and 72 of thereference and roving voltage signals REF and ROV, respectively.

The amplitude of the voltage signal ROV corresponding to the rovingelectrode 31 is also shown on panel 66 of FIG. 5. The amplitude of thetime-varying signal ROV is located between two adjustable bands 74 and76, which can be used to set selection criteria for the peak-to-peakvoltage of the signal ROV. In practice, regions of the heart with lowpeak-to-peak voltage are the result of infarct tissue, and the abilityto convert the peak-to-peak voltage to grayscale or false color allowsidentification of the regions that are infarct or ischemic. In addition,a time-varying signal “V1” is also shown and corresponds to a surfacereference electrode, such as a conventional ECG surface electrode. Thesignal V1, for example, may orient a user, such as a physician, to thesame events detected on the surface of the patient.

As described above, the electrodes of at least one EP catheter are movedover the surface of the heart and while in motion they detect theelectrical activation of the heart or other EP signals on the surface ofthe heart. During each measurement, the real-time location of thecatheter electrode is noted along with the value of the EP voltage orsignal. This data is then projected onto a surface of thethree-dimensional model corresponding to the location of the electrodewhen the sampled EP data was taken. Since this data is not taken whilethe locating surface electrodes are energized, a projection process maybe used to place the electrical information on the nearest heartsurfaces represented by the geometry. In one exemplary embodiment, forexample, two close points or locations in the EP data set are selected,and the data is mapped to a point determined to be the closer of the twopoints (e.g., via “dropping” a line to the “nearest” surface point onthe geometric surface). This new point is used as the “location” for thepresentation of EP data in the images presented to the physician.

Various time-domain information related to the EP activity in and/oraround the heart of a patient may be mapped to the three-dimensionalmodel. For example, the time difference of an action potential measuredat a roving electrode and a reference electrode, the peak-to-peakvoltage of an action potential measured at the roving electrode, and/orthe peak negative voltage of an action potential measured at the rovingelectrode may be mapped to a three-dimensional model. In one embodiment,EP activity from up to sixty-two roving electrodes may be collected andmapped to the three-dimensional model.

Complex fractionated electrogram (CFE) and frequency-domain informationmay also be mapped to the three-dimensional model. CFE information, forexample, may be useful to identify and guide ablation targets for atrialfibrillation. CFE information refers to irregular electrical activation(e.g., atrial fibrillation) in which an electrogram comprises at leasttwo discrete deflections and/or perturbation of the baseline of theelectrogram with continuous deflection of a prolonged activation complex(e.g., over a 10 second period). Electrograms having very fast andsuccessive activations are, for example, consistent with myocardiumhaving short refractory periods and micro-reentry. FIG. 6, for example,shows a series of electrograms. The first two electrograms, RAA-prox andRAA-dist, comprise typical electrograms from the right atrium of apatient such as from a proximal roving electrode and a distal rovingelectrode in the right atrium of a patient, respectively. The thirdelectrogram, LA-roof, comprises a CFE, such as from the roof of thepatient's left atrium. In this third electrogram, LA-roof, the cyclelengths indicated by the numbers shown in the electrogram aresubstantially shorter than the cycle lengths indicated by the numbersshown in the first two electrograms, RAA-prox and RAA-dist. In anotherexample shown in FIG. 7, a first electrogram RA-Septum comprises fastand successive activations indicated by the arrows compared to thesecond electrogram RA. The fast and successive activations, for example,can be consistent with myocardial tissue having short refractory periodsand micro-reentry, e.g., an atrial fibrillation “nest.”

The presence of CFE information can be detected from the EP information(e.g., electrograms) collected by an electrode, for example, bymonitoring the number of deflections within an electrogram segment;calculating the average time between deflections within an electrogramsegment; monitoring the variation of time between deflections within acycle length of an electrogram; and calculating slopes, derivatives, andamplitudes of electrograms. For example, discrete activations have anassociated peak-to-peak value measured over a specified time period.This peak-to-peak value may be used to quantify a discrete activation.As shown in FIG. 5, a time instant of the discrete activations can bemarked on the electrogram on the user display. The time instant and/orother quantifications of the fractionation of the electrogram may beused to determine the presence and/or absence of CFE information. Themean interval between discrete activations within a predetermined timeperiod may, for example, be used as an index to quantify the degree offractionation of a given electrogram. In this example, a value of onemay be assigned to the electrogram if there is only one discreteactivation within the given time period, and a lesser or higher valuemay be assigned if more than one discrete activation is present in thegiven time period. Another quantification may comprise, for example,quantifying the variance in time between discrete activations of anelectrogram. These or other quantifications of the time-domain correlatewith the morphology of the electrogram and are, in turn, based upon theunderlying physiology of the region for which the electrogram wassampled.

Preferably, the mean interval between discrete activations within apredetermined time period may be calculated for a plurality of locationswithin the heart, so that comparisons may be made from one location onthe heart to another. This may be accomplished using a plurality ofelectrodes, or by using the same electrodes repositioned at a pluralityof locations. Software may be used to display mean interval informationas a function of location on the heart, for example, by assigning colorsto various measured values. Such software provides the user of thesystem with a visual tool to help identify potential problem areas.

In a preferred embodiment, a standard deviation calculation is desiredfor the CFE information. It has been discovered that standard deviationcalculations for CFE information provide a useful metric for determiningthe presence and/or absence of CFE information, and accordingly, is auseful metric for identifying areas that may need ablating. The presenceof CFE information can be detected from the EP information (e.g.,electrograms) collected by an electrode, for example, by monitoring thenumber of deflections within an electrogram segment and calculating thestandard deviation of the time intervals between discrete activationswithin an electrogram segment. As discussed above in connection withFIG. 5, the occurrence of the discrete activations can be marked on theelectrogram on the user display. It is also possible to utilize softwareto analyze and identify the occurrences of discrete activations, whichinformation may then be evaluated for standard deviations. Standarddeviations measurements may be calculated using known algorithms onsections of data for time periods of less than 1 second or for muchlonger time periods of several seconds, such as 20-60 seconds.Preferably, the time period ranges from about 1 second to about 10seconds, and more preferably for time periods ranging from about 3seconds to about 8 seconds. In one embodiment, the user may specify thewindow for analysis. Preferably, standard deviation determinations aremade for multiple locations within a portion of the heart, so thatcomparisons may be made from one location on the heart to another. Thismay be accomplished using a plurality of electrodes, or by using thesame electrodes repositioned at a plurality of locations. Software maybe used to display standard deviation information as a function oflocation on the heart, for example, by assigning colors to variousmeasured values. Such software provides the user of the system with avisual tool to help identify potential problem areas. When the standarddeviation exceeds a particular threshold, this may indicate a highdegree of fractionation in the electrogram.

In yet another preferred embodiment, the CFE information is presentedusing both mean interval data and standard deviation of the intervals.Preferably, the mean and standard deviation information for intervalsbetween discrete activations within a predetermined time period arecalculated for a plurality of locations within the heart, so thatcomparisons may be made from one location on the heart to another.Software may be used to display mean and standard deviation informationas a function of location on the heart, for example, by assigning colorsto various measured values. This may take the form of two separateimages that may be compared to each other—or a single image in which thetwo sets of data are superimposed upon the same three-dimensional model.Another way to display the combined information is to mathematicallyrelate the two metrics, for example, the standard deviation divided bythe mean, or the mean divided by the standard deviation, and thendisplay the result on a single image, again assigning colors to variouscalculated values. Such presentation software provides the user of thesystem with a visual tool to help identify potential problem areas usingboth mean and standard deviation information. A physician, for example,may find it of significance that a particular location has a highstandard deviation and a low mean. A goal of this invention is toprovide tools to help a physician analyze the situation using as muchuseful information as possible.

In diagnosing atrial fibrillation and guiding an ablation catheter, theelectrograms corresponding to physiological mechanisms for initiatingand sustaining atrial fibrillation may be identified by quantifying thefractionation of the electrograms. These quantifications, in turn, maybe used to identify regions to be ablated to eliminate the atrialfibrillation. Mid-diastolic potentials within an ischemic area of thecardiac chamber may also be identified by quantifying the fractionationof the electrograms collected in a region of the heart. Healthy tissuewould correspond to non-fractionated electrograms (i.e., a singlediscrete activation), while unhealthy tissue (e.g., ischemic tissue)would correspond to fractionated electrograms (i.e., multiple discreteactivations and/or perturbations of the baseline). The time instant orother quantifications of CFE information in electrograms may then bemapped to a three-dimensional model as described above.

In addition to and/or alternatively to the time-domain informationanalyzed and mapped from the collected EP information, frequency-domaininformation may also be mapped to a three-dimensional model. In oneembodiment, for example, a fast Fourier transform (FFT) or other methodof translating a time-varying signal into frequency-domain informationmay be used to translate the collected signal into a frequency-domain.The frequency-domain depicts a spectrum that represents the energy orpower of frequency components of a time-varying electrogram signal. FFTsand other transforms are known in the art and are not discussed infurther detail herein.

FIG. 8 shows a side-by-side comparison of compact myocardial muscle andfibrillar myocardial muscle that together form the wall of the heart.Compact myocardial muscle tissue comprises groups of tightly-connectedcells that conduct electrical activity during depolarization of theheart in a homogenous fashion by transmitting electrical activity atequal speeds in any direction. Fibrillar myocardial muscle tissue,however, typically comprises loosely connected cells, such astransitions between neural, vascular, and atrial tissue. Fibrillarmyocardial muscle tissue may also be formed by stretching and/ordegeneration of cells leading to poor connections between such damagedtissue. In row A, the first column shows the homogenous or uniformactivation of compact myocardial muscle tissue during depolarization ofthe heart wall. In the second column, however, the irregular activationof fibrillar myocardial muscle tissue is shown during depolarization inwhich a wave travels at different rates through different strands orportions of the fibrillar myocardial muscle tissue, thus causingasynchronous contraction in different portions of the myocardium.

In row B, time-domain electrogram signals are shown for the compactmyocardial muscle tissue and the fibrillar myocardial muscle tissueduring a depolarization phase of a heartbeat. As shown in FIG. 8, thetime-domain electrogram signals typically comprise a biphasic ortriphasic shape for compact myocardial muscle tissue (shown in column 1)and a more polyphasic shape for fibrillar myocardial muscle tissue(shown in column 2). Finally, the frequency-domain of the electrogramsignals of row B for compact myocardial muscle tissue and fibrillarmyocardial muscle tissue is shown in row C. The frequency-domain isobtained by performing an FFT on a time period of the time-varyingelectrograms shown row B, column 1 for compact myocardial muscle tissueand row B, column 2 for fibrillar myocardial muscle tissue. As shown inrow C of FIG. 8, the frequency-domain for compact myocardial muscletissue typically comprises a higher amplitude at a single peak locatedaround a fundamental frequency, while the frequency-domain for thefibrillar myocardial muscle tissue typically comprises a lower amplitudeat its fundamental frequency due to a right-shift of the frequencycaused by a number of harmonic frequency components.

As shown in FIG. 8, fibrillar myocardial muscle tissue can lead toirregular wavefronts of electrical activity during depolarization of theheart. The greater the ratio of fibrillar myocardial muscle tissue tocompact myocardial muscle tissue, the more likely there is a propensityfor atrial fibrillation. In such areas “atrial fibrillation nests” (or“AFIB nests”) may be identified as potential sources of atrialfibrillation. Thus, by use of frequency-domain information, a physicianmay be able to further identify potential trouble spots that may lead toatrial fibrillation.

Various numerical indices can be obtained from the frequency-domain ofthe electrogram signal. Any of these indices can then be mapped to athree-dimensional model of a patient's heart to allow a user such as aphysician to identify locations on the wall of the heart that correspondto a particular characteristic. In one exemplary variation of thepresent invention, a dominant frequency of an electrogram signal can beidentified in the frequency-domain, which has been obtained via an FFT.As can be seen in FIG. 9A, for example, a typical normal, or compact,myocardial muscle tissue may have a single peak in the spectrum, while afibrillar myocardial muscle tissue has more spectral peaks than does acompact myocardial muscle tissue. The number of spectral peaks may bedetermined for multiple points around the wall of the heart on athree-dimensional model as described above.

In another variation of the present invention, a maximum peak amplitudeat the dominant frequency may be determined from the frequency-domain ofthe electrogram signal and may be mapped to a three-dimensional model ofthe heart. In FIG. 9A, for example, the maximum peak amplitude at thedominant frequency of compact myocardial muscle tissue can be seen to behigher at about 175 dB mV, while the maximum peak amplitude at thedominant frequency of fibrillar myocardial muscle tissue is lower atabout 80 dB mV. These values may also be mapped onto a three-dimensionalmodel of the heart.

In yet another variation, a ratio of energy in one band of thefrequency-domain to the energy in a second band of the frequency-domainmay be determined and mapped to a three-dimensional model of the heart.For example, FIG. 9B shows the ratio of energy in the passband of 60 to240 Hz to the energy below 60 Hz is higher for the spectrum ofelectrograms from fibrillar myocardial muscle tissue than in thespectrum of electrograms from compact myocardial muscle tissue.

While examples of time-domain and frequency-domain information have beendescribed herein as able to be translated to a three-dimensional map ofa patient's heart, one skilled in the art would recognize that othertime- and frequency-domain information may also be determined and mappedto a three-dimensional model. For example, the following information maybe determined from the time-domain or frequency-domain and mapped to athree-dimensional model: a low-frequency or high-frequency passband ofinterest (e.g., in Hz); a frequency with the maximum energy in apassband (e.g., in Hz); a number of peaks within a passband (e.g., acount); an energy, power, and/or area in each peak (e.g., dB); a ratioof energy and/or area in each peak to that in another passband; and awidth of each peak in a spectra (e.g., in Hz).

FIG. 10 shows one example of a method for determining information from atime-varying electrogram in the time-domain and/or frequency-domain andmapping that information onto a three-dimensional model (e.g., a heart).In operation 100, a number of electrodes (e.g., contact or non-contact,unipolar or bipolar mapping electrodes) are used to sample atime-varying electrogram signal. The electrogram signal, for example,may be sampled for multiple sites along the wall of the heart and/or thesurrounding vasculature.

An FFT is then performed over a time period of the time-varyingelectrogram to determine frequency-domain information for thatelectrogram in operation 102. A real-time display of the time-domainand/or frequency-domain information may be displayed in operation 104.One or more parameters are then determined in operation 106. Exemplaryparameters are described above and include, for example, a timedifference between a roving electrode and a reference electrode; thepeak-to-peak voltage of the roving electrode; the peak negative voltageof the roving electrode; CFE information; a dominant frequency of anelectrogram signal; a maximum peak amplitude at the dominant frequency;a ratio of energy in one band of the frequency-domain to the energy in asecond band of the frequency-domain; a low-frequency or high-frequencypassband of interest; a frequency with the maximum energy in a passband;a number of peaks within a passband; an energy, power, and/or area ineach peak; a ratio of energy and/or area in each peak to that in anotherpassband; and a width of each peak in a spectrum. Colors, shades ofcolors, and/or grayscales are assigned to values of the parameters to beidentified in operation 108, and colors, shades of colors, and/orgrayscales corresponding to the parameters for the electrograms sampledby the electrodes are updated on a three-dimensional model (e.g., of aheart) continuously and in real time in operation 110.

One particular area of interest is the mapping of areas of the heartcomprised of autonomic nerve cells. ECG information may be mapped toidentify the foci of electrical propagation through the heart. Theinitiation points for electrical signals will generally be autonomiccell bundles, or ganglia plexi. To the extent that any arrhythmia iscaused by a malfunction in autonomic cells, the ability to detect thismalfunction can significantly aid in the efficacy of treatment andminimize the scope of treatment. A particular advantage to mapping thecomplex fractionated electrograms in the frequency domain is the abilityto quickly identify and locate such areas of arrhythmia. For example, ifit is determined that a specific autonomic bundle is the source offibrillation, targeting this area of initial neural input instead oftreating multiple areas of fibrillar tissue can substantially reduce thenumber of lesions required to treat the condition.

Although multiple embodiments of this invention have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this invention. For example, whilethe description above describes data being mapped to a three-dimensionalmodel, data may be mapped to any map including, but not limited to, atwo- or three-dimensional, static or time-varying image or model.

All directional references (e.g., upper, lower, upward, downward, left,right, leftward, rightward, top, bottom, above, below, vertical,horizontal, clockwise, and counterclockwise) are only used foridentification purposes to aid the reader's understanding of the presentinvention, and do not create limitations, particularly as to theposition, orientation, or use of the invention. Joinder references(e.g., attached, coupled, connected, and the like) are to be construedbroadly and may include intermediate members between a connection ofelements and relative movement between elements. As such, joinderreferences do not necessarily infer that two elements are directlyconnected and in fixed relation to each other.

It is intended that all matter contained in the above description orshown in the accompanying drawings shall be interpreted as illustrativeonly and not limiting. Changes in detail or structure may be madewithout departing from the spirit of the invention as defined in theappended claims.

1. A system for presenting information representative ofelectrophysiological activity of a patient, the system comprising: atleast one electrode adapted to receive at least one stream of electricaldata from at least one location within a heart of a patient, said datacomprising complex fractionated electrogram information; at least oneprocessor coupled to the at least one electrode to receive the at leastone stream of electrical data from at least one location and todetermine the measurement location of the electrode within the heart ofthe patient while it is receiving the stream of electrical data, said atleast one processor associating the measurement location with the atleast one stream of electrical data being received; at least one memoryto store the measurement location of the electrode and the at least onestream of electrical data being received; software to analyze the atleast one stream of electrical data to identify occurrences of discreteelectrical activations within a predetermined window, and to quantifythe complex fractionated electrogram information contained in thepredetermined window; and a presentation device to present saidquantified complex fractionated electrogram information and itsrespective measurement location on a model of the heart of the patient.2. The system of claim 1, wherein the software quantifies the standarddeviation of the time intervals between occurrences of discreteelectrical activations within the predetermined window, and wherein thepresentation device presents the standard deviation information on themodel of the heart at a location that corresponds to a point at whichthe electrical data was measured.
 3. The system of claim 2, wherein thesoftware also quantifies the mean time intervals between occurrences ofdiscrete electrical activations within the predetermined window; whereinthe presentation device presents the standard deviation information onthe model of the heart at a location that corresponds to a point atwhich the electrical data was measured; and wherein the presentationdevice also presents the mean interval information on the model of theheart at a location that corresponds to a point at which the electricaldata was measured.
 4. The system of claim 1, wherein the softwarequantifies the mean time intervals between of the occurrences ofdiscrete electrical activations within the predetermined window, andwherein the presentation device presents the mean interval informationon the model of the heart at a location that corresponds to a point atwhich the electrical data was measured.
 5. The system of claim 1,wherein the at least one electrode comprises a plurality of electrodesadapted to receive electrical data simultaneously from a plurality oflocations within the patient; wherein the processor receives a pluralityof streams of electrical data from the plurality of electrodes,determines the measurement locations of each of the plurality ofelectrodes, and associates each measurement location with the stream ofelectrical data that is measured at the respective measurement location;wherein the software analyzes each of the plurality of streams of datato identify occurrences of discrete electrical activations within apredetermined window, and quantifies the complex fractionatedelectrogram information contained in each predetermined window of theplurality of streams of data; and wherein the presentation devicepresents the quantified complex fractionated electrogram information foreach of a plurality of streams of data at a plurality of locations,wherein each of the plurality of locations corresponds to a location inthe heart at which the underlying electrical data was measured.
 6. Thesystem of claim 1, wherein the presentation device presents thequantified complex fractionated electrogram information by assigning atleast one color, shade of color, or grayscale to represent the complexfractionated electrogram information on a model of the heart.
 7. Amethod of analyzing and presenting information representative ofelectrophysiological activity of a patient, comprising the steps of:obtaining a cardiac electrophysiology map comprising positioninformation identifying a plurality of measurement locations andelectrophysiology measurements made at each of the plurality ofmeasurement locations, said electrophysiology measurements comprising atleast one stream of complex fractionated electrogram information;processing the at least one stream of complex fractioned electrograminformation measured at one of the plurality of measurement locations toidentify occurrences of discrete electrical activations within apredetermined window, and to quantify the complex fractionatedelectrogram information contained in the predetermined window; andpresenting the quantified complex fractionated electrogram informationand its respective measurement location on a model of the heart of thepatient.
 8. The method of claim 7, wherein the processing step furthercomprises quantifying the standard deviation of the time intervalsbetween occurrences of discrete electrical activations within thepredetermined window, and wherein the presenting step further comprisespresenting the standard deviation information on the model of the heartat a location that corresponds to a point where the electrical data wasmeasured.
 9. The method of claim 8, wherein the processing step furthercomprises quantifying the mean time intervals between occurrences ofdiscrete electrical activations within the predetermined window; whereinthe presenting step further comprises presenting the standard deviationinformation on the model of the heart at a location that corresponds toa point at which the electrical data was measured; and wherein thepresenting step further comprises presenting the mean intervalinformation on the model of the heart at a location that corresponds toa point at which the electrical data was measured.
 10. The method ofclaim 7, wherein the processing step further comprises quantifying themean time intervals between occurrences of discrete electricalactivations within the predetermined window, and wherein the presentingstep further comprises presenting the mean interval information on themodel of the heart at a location that corresponds to a point where theelectrical data was measured.
 11. The method of claim 7, wherein thestep of obtaining a cardiac electrophysiology map further comprises:using a plurality of electrodes to receive electrical datasimultaneously from a plurality of measurement locations within thepatient; and obtaining a cardiac electrophysiology map comprisingposition information identifying a plurality of measurement locationsand electrophysiology measurements made at each of the plurality ofmeasurement locations, said electrophysiology measurements comprising atleast one stream of complex fractionated electrogram information;wherein the step of processing the stream of complex fractionedelectrogram information further comprises processing each of theplurality of streams of data to identify occurrences of discreteelectrical activations within a predetermined window, and quantifyingthe complex fractionated electrogram information contained in eachpredetermined window of the plurality of streams of data; and whereinthe step of presenting the quantified complex fractionated electrograminformation further comprises presenting the quantified complexfractionated electrogram information for each of a plurality of streamsof data at a plurality of locations, wherein each of the plurality oflocations corresponds to a location in the heart at which the underlyingelectrical data was measured.
 12. The method of claim 7, wherein thepresenting step further comprises presenting the quantified complexfractionated electrogram information by assigning at least one color,shade of color, or grayscale to represent the complex fractionatedelectrogram information on a model of the heart.
 13. A method ofanalyzing and presenting information representative ofelectrophysiological activity of a patient, comprising the steps of:obtaining a cardiac electrophysiology map comprising positioninformation identifying a measurement location and electrophysiologymeasurements made at the measurement locations, said electrophysiologymeasurements comprising at least one stream of complex fractionatedelectrogram information; processing the at least one stream of complexfractioned electrogram information measured at the measurement locationsto identify occurrences of discrete electrical activations within apredetermined window, and to quantify the standard deviation of the timeintervals between occurrences of discrete electrical activations withinthe predetermined window; and presenting the standard deviationinformation on the model of the heart at a location that corresponds toa point where the at least one stream of complex fractioned electrograminformation was measured.
 14. A system for presenting informationrepresentative of electrophysiological activity of a patient, the systemcomprising: at least one electrode adapted to measure electrograminformation from a surface of a heart of a patient; at least oneprocessor coupled to the at least one electrode to receive theelectrogram information and to measure a location of the at least oneelectrode within the heart of the patient at which the electrograminformation is measured, wherein said at least one processor associatesthe measured location of the at least one electrode with the receivedelectrogram information; and a presentation device to present theassociated electrogram information and measured location on a model ofthe heart of the patient.
 15. The system according to claim 14, whereinthe electrogram information comprises complex fractionated electrograminformation.
 16. The system according to claim 14, further comprising atleast one memory in which to store the associated electrograminformation and measured location.
 17. A method of presentinginformation representative of patient electrophysiologicalcharacteristics on a model of a surface of a heart, comprising the stepsof: a) introducing at least one electrode into the heart; b) measuringelectrogram information from the surface of the heart via the at leastone electrode; c) measuring location information of the at least oneelectrode; d) deriving, from the measured location information, locationinformation for a point on the surface of the heart at which theelectrogram information is measured; e) associating the derived locationinformation and measured electrogram information; and f) presentinginformation indicative of the associated location information andelectrogram information on the model of the surface of the heart. 18.The method according to claim 17, further comprising repeating steps b),c), d), e), and f) a plurality of times as the electrode moves withinthe heart.
 19. The method according to claim 17, wherein the step ofintroducing at least one electrode into the heart comprises introducinga plurality of electrodes into the heart, and further comprisingrepeating steps b), c), d), e), and f) for each of the plurality ofelectrodes.
 20. The method according to claim 17, wherein the step ofpresenting information indicative of the associated location informationand electrogram information on the model of the surface of the heartcomprises the steps of: quantifying the measured electrograminformation; and presenting the quantified electrogram information onthe model of the surface of the heart.
 21. The method according to claim20, wherein the quantified electrogram information comprises time-domainelectrogram information.
 22. The method according to claim 21, whereinthe time-domain electrogram information comprises one or more items ofinformation selected from the group consisting of: a time differencebetween action potentials measured at the at least one electrode and areference electrode; a peak-to-peak voltage of an action potentialmeasured at the at least one electrode; and a peak negative voltage ofan action potential measured at the at least one electrode.
 23. Themethod according to claim 20, wherein the quantified electrograminformation comprises frequency-domain electrogram information.
 24. Themethod according to claim 23, wherein the frequency-domain electrograminformation comprises one or more items of information selected from thegroup consisting of: a dominant frequency of the electrograminformation; a maximum peak amplitude at the dominant frequency of theelectrogram information; and a ratio of energy in a first band of thefrequency domain to energy in a second band of the frequency domain. 25.The method according to claim 19, wherein the quantified electrograminformation is based on a standard deviation of the measured electrograminformation.
 26. The method according to claim 19, wherein thequantified electrogram information is based on a mean of the measuredelectrogram information.
 27. The method according to claim 19, whereinthe quantified electrogram information is based on a ratio between amean of the measured electrogram information and a standard deviation ofthe measured electrogram information.
 28. The method according to claim19, wherein the quantified electrogram information is based on avariance in the measured electrogram information.
 29. The methodaccording to claim 19, wherein the quantified electrogram information isbased on a number of discrete activations present in a predeterminedtime period.
 30. The method according to claim 17, wherein the step ofpresenting information indicative of the associated measured locationinformation and measured electrogram information on the model of thesurface of the heart comprises projecting one or more isochrones on themodel of the surface of the heart.